Ballast water treatment system

ABSTRACT

The present invention provides a ballast water treatment system, comprising a centrifugal separator, an ultrasonic sterilizer, and an ultraviolet sterilizer, wherein, the centrifugal separator is designed to separate large-particle of foreign matters from the ballast water by centrifugal separation by means of density difference; the ultrasonic sterilizer is arranged at the back of the centrifugal separator, and is designed to accomplish ultrasonic sterilization for the ballast water passing through the centrifugal separator; the ultrasonic sterilizer comprises a pipe that is used for sterilization of the ballast water and ultrasonic irradiation unit that perform ultrasonic irradiation for the ballast water passing through the pipe; the ultraviolet sterilizer accomplishes sterilization by means of ultraviolet irradiation for the ballast water passing through the ultrasonic sterilizer. The ballast water treatment system provided in the present invention can effectively accomplish sterilization for the ballast water that flows into the ballast tank of ship, and thereby prevent all kinds of pollution to seawater related with ballast water discharge, and greatly improve reliability of application.

FIELD OF THE INVENTION

The present invention relates to a water treatment system, in particularto a ballast water treatment system.

BACKGROUND OF THE INVENTION

For large ships, in order to keep its balance during sailing,appropriate volume of seawater needs to be stored in the ballast tank atthe bottom of the ship. The seawater or fresh water stored in theballast tank for keeping balance of ship is known as ballast water.

Usually, ballast water is stored in the ballast tank near the port ofdeparture, and after a voyage discharged from the ballast tank in theoffshore area near the port of destination.

However, the ballast water charged into the ballast tank of the ship inthe offshore area near the port of departure contains a variety ofmicrobes that live in the offshore area or silt, and therefore theballast water will pollute the offshore environment near the port ofdestination when it is discharged.

To solve the problem, a treaty for regulation and management of shipballast water and sediments (hereinafter referred as “Treaty for BallastWater”) is adopted, and it specifies the discharge standard of ballastwater. Ballast water is prohibited to discharge if the dischargestandard is not met.

To meet the ballast water discharge standard, a variety of proposals forinstallation of ballast water treatment system in ship are put forth.The Korean Patent Application No. 10-0743946, titled as “Apparatus forPurifying Ballast Water and Ship Mounted the Same”, describes a method,wherein the ballast water stored in the tank is treated with a filteringapparatus during storage, and the ballast water is sterilized with asterilizing apparatus before it is discharged, which is to say,large-particle materials are filtered off with the filtering apparatus,and then a variety of planktonic organisms or microbes are sterilizedunder UV irradiation with the sterilizing equipment.

The present ballast water treatment systems mounted inside ships are nothighly reliable, and their sterilization and purification effects arenot ideal. Therefore, the ballast water still brings pollution to theoffshore environment of the port of destination.

SUMMARY OF THE INVENTION

To overcome the drawbacks of the prior art, the object of the presentinvention is to provide a ballast water treatment system, which has highreliability and can effectively accomplish sterilization of the ballastwater that flows into the ship, and thereby can prevent pollutionresulting from discharge of ballast water.

To solve the above problem, the ballast water treatment system providedin the present invention comprises a centrifugal separator, anultrasonic sterilizer, and an ultraviolet sterilizer, wherein:

the centrifugal separator is designed to separate large particle offoreign matters in the ballast water by centrifugal separation by meansof density difference;

the ultrasonic sterilizer is arranged at the back of the centrifugalseparator, and is designed to accomplish ultrasonic sterilization forthe ballast water in the centrifugal separator;

the ultrasonic sterilizer comprises a pipe that is used forsterilization of the ballast water and ultrasonic irradiation unit thatperform ultrasonic irradiation for the ballast water in the pipe;

the ultraviolet sterilizer is designed to accomplish sterilization ofthe ballast water in the ultrasonic sterilizer by means of ultravioletirradiation.

Wherein, the ultrasonic irradiation unit comprises: an ultrasonicvibrator that generates ultrasonic vibration and a vibrating plate thatis mounted at the fore-end of the ultrasonic vibrator and is designed totransfer the ultrasonic wave generated by the ultrasonic vibrator to theballast water in the pipe.

Wherein, a plurality of vibrating plates are aligned along the lengthdirection of the pipe for sterilization, and are mounted along thecircumference of the pipe for sterilization, and each vibrating platecomprises a plurality of ultrasonic vibrators in the length direction ofthe vibrating plate.

Wherein, the ultrasonic vibrator comprises high-frequency vibrators andlow-frequency vibrators, which are mounted alternately in the lengthdirection of the vibrating plate.

Wherein, in order to transfer ultrasonic wave in the pipe forsterilization, a roll shape metal mesh which is tangent to the vibratingplate is mounted in the pipe for sterilization.

Wherein, an acoustic material is mounted at the inside of the ultrasonicsterilizer, and a protective cover that envelops the ultrasonicvibrators is mounted at the outside of the pipe for sterilization.

Wherein, the diameter of the discharge pipe of the centrifugal separatorincreases gradually, and the flow velocity of fluid increases, therebythe centrifugal force increases.

Wherein, a protective cover for the ultrasonic irradiation unit ismounted on the ultrasonic sterilizer.

Wherein, the ultraviolet sterilizing equipment is further equipped withan explosion-proof cover plate.

As described above, in the present invention, with a resonablecombination of centrifugal separator, ultrasonic sterilizer, andultraviolet sterilizer, the ballast water in the ship can be sterilizedeffectively, so as to prevent a variety of sea pollution related withdischarge of ballast water. Therefore, the ballast water treatmentsystem provided in the present invention has high reliability.

DESCRIPTION OF DRAWINGS

FIG. 1A and FIG. 1B are system diagrams of embodiment 1 of the ballastwater treatment system provided in the present invention;

FIG. 2 is a flow diagram of fluid when ballast water flows into theballast tank on the basis of FIG. 1A and FIG. 1B;

FIG. 3 is a flow diagram of fluid when ballast water discharges on thebasis of FIG. 1A and FIG. 1B;

FIG. 4A and FIG. 4B are 3D diagrams of main components of the ballasttreatment system shown in FIG. 1A and FIG. 1B;

FIG. 5A and FIG. 5B are front views of FIG. 4A and FIG. 4B;

FIG. 6 is a 3D diagram of the centrifugal separator shown in FIG. 4A andFIG. 4B;

FIG. 7 is a schematic diagram of operation of FIG. 6;

FIG. 8 is a 3D schematic diagram of structure 1 of the ultrasonicsterilizer shown in FIG. 4A and FIG. 4B;

FIG. 9A and FIG. 9B are longitudinal section views of FIG. 8;

FIG. 10 is a plan view of FIG. 8;

FIG. 11A and FIG. 11B are 3D diagrams of FIG. 8, with the protectivecover removed;

FIG. 12 is a 3D schematic diagram of structure 2 of the ultrasonicsterilizer shown in FIG. 4A and FIG. 4B;

FIG. 13A and FIG. 13B are front views of the ultraviolet sterilizershown in FIG. 4A and FIG. 4B;

FIG. 14 shows the metal mesh arranged in the ultrasonic sterilizer formore efficiently transferring ultrasonic wave;

FIG. 15 is a system diagram of embodiment 2 of the ballast watertreatment system provided in the present invention;

FIG. 16 is a front view of the ultraviolet sterilizer shown in FIG. 15;

FIG. 17 is a longitudinal section view of the explosion-proof ultrasonicsterilizer;

FIG. 18 is a front view of the explosion-proof ultrasonic sterilizer.

<Description of the Symbols> 10 Water Pump 20 Ballast Tank 100Centrifugal 200 Ultrasonic Sterilizer Separator 210 Pipe for 220Ultrasonic Irradiation Sterilization Unit 221 Ultrasonic 222 VibratingPlate Vibrator 230 Protective Cover 231 Acoustic Material 240 Metal Mesh241~246 Upper Vibrating Plate 251, 252, 256 Lower Vibrating 261Explosion-Proof Plate Protective Cover for Ultrasonic Vibrator 300Ultraviolet Sterilizer

DETAILED DESCRIPTION OF THE EMBODIMENTS

For those skilled in the art to implement the present invention,hereunder the embodiments of the present invention will be described indetail with reference to the accompanying drawings. However, it shouldbe appreciated that the present invention can be implemented indifferent forms, and not limited to the embodiments described here. Inaddition, for the clear illustration on the drawings, parts that areunnecessary for description are omitted, and same drawing symbols referto similar parts throughout the whole specification.

While the present invention is described in detail with reference tosome embodiments, those embodiments are not intended to limit thepresent invention. Those skilled in the art can make modifications tothe technical scheme described in the embodiments, or make equivalentreplacements to some technical features of the embodiments. However, anymodification, equivalent replacement, or improvement to the embodimentswithout departing from the spirit and principle of the present inventionshall be deemed as falling into the protected scope of the presentinvention.

To make the composition of the ballast water treatment system moreeffective, the ultrasonic sterilizer and ultraviolet sterilizer, whichare components of the ballast water treatment system, are constitutedwith two models in the specification of the present invention.

Embodiment 1

FIG. 1A and FIG. 1B are system diagrams of embodiment 1 of the ballastwater treatment system provided in the present invention. As shown inFIG. 1A and FIG. 1B, the ballast water treatment system comprises: awater pump (10), a ballast tank (20), a centrifugal separator (100), anultrasonic sterilizer (200), and an ultraviolet sterilizer (300).

FIG. 2 is a flow diagram of fluid when ballast water flow into theballast tank on the basis of FIG. 1A and FIG. 1B. As shown in FIG. 2,the process of charging ballast water into the ballast tank (20) is asfollows: the ballast water flows into the ballast tank (20) through thewater pump (10), centrifugal separator (100), ultrasonic sterilizer(200), and ultraviolet sterilizer (300).

FIG. 3 is a flow diagram of fluid when ballast water discharges on thebasis of FIG. 1A and FIG. 1B. As shown in FIG. 3, the process ofdischarging ballast water from the ballast tank (20) is as follows: theballast water is discharged to the outside from the ballast tank (20)through the water pump (10), ultrasonic sterilizer (200), andultraviolet sterilizer (300).

In the ballast water treatment system provided in the present invention,the ballast water flows through the centrifugal separator (100) when itis ballasted, but it doesn't flows through the centrifugal separator(100) when it is discharged, since it has been treated by centrifugalseparation.

FIG. 4A and FIG. 4B are 3D diagrams of main components of FIG. 1A andFIG. 1B; FIG. 5A and FIG. 5B are front views of FIG. 4A and FIG. 4B. Asshown in FIG. 4A, FIG. 4B, FIG. 5A, and FIG. 5B, the main structure ofthe system is a structure in which the centrifugal separator (100),ultrasonic sterilizer (200), and ultraviolet sterilizer (300) arearranged sequentially in the flow direction of fluid as shown in FIG.4A, FIG. 4B, FIG. 5A, and FIG. 5B.

FIG. 6 is a 3D diagram of the centrifugal separator shown in FIG. 4A andFIG. 4B. As shown in FIG. 6, the centrifugal separator (100) in thisembodiment is a cyclone centrifugal separator.

The centrifugal separator (100) is designed to separate large-particleof foreign matters from the ballast water by centrifugal separation bymeans of density difference, when the ballast water flows into theballast tank.

That is to say, when the ballast water flows into the ballast tankthrough the centrifugal separator (100), it rotates in the centrifugalseparator (100) and therefore centrifugal force is generated in therotating water; as a result, high-density particles gather at theconical inner wall and are discharged to the outside through the conevertex. After the high-density particles are separated, the ballastwater flows out from the top of the centrifugal separator (100), andthen flows into the next process, i.e., ultrasonic sterilizer (200).

FIG. 7 is a schematic diagram of operation of FIG. 6. As shown in FIG.7, the diameter (D1, D2) of the discharge pipe (110) is enlarged from D1to D2 gradually, so that the ballast water rotating inside flows faster.That design is to increase the centrifugal force of ballast water(center distance×square of flow velocity) at the inlet caliber (D2) ofthe discharge pipe (110), so as to improve the efficiency of centrifugalseparator.

The centrifugal separator (100) is connected to the ultrasonicsterilizer (200) at the backend.

The ultrasonic sterilizer (200) is provided to carry out ultrasonicsterilization for the ballast water through the centrifugal separator(100).

Ultrasonic wave is sound in a frequency range beyond the hearing rangeof human being, and carries very powerful energy. Ultrasonic wave istransferred to liquids in the form of dilatational wave, and therebygenerates a strong cavitation effect in the liquids.

Such ultrasonic wave is usually used for washing or cleaning. Forexample, the ultrasonic wave can be used in ultrasonic equipment formedical diagnosis, for ultrasonic cleaning of optical glasses, forcleaning of automotive parts, and for cleaning of ceramic, etc.(ultrasonic washing machine, ultrasonic disintegrator, cleaning ofdental medical equipment, and cleaning of noble metals, etc.)

In addition to above contents, the sterilizing effect of ultrasonicirradiation in liquid has been proved in many literatures. However,since ultrasonic irradiation will generate very big noise, it is notwidely used in industrial field for sterilization purpose yet.

In the ballast water treatment system of present invention, theultrasonic sterilizer (200) is arranged at the fore end of theultraviolet sterilizer (300), to kill planktonic organisms or microbesby means of the perfect combination of ultrasonic sterilizer (200) andultraviolet sterilizer (300), to ensure the treated ballast water complywith the discharge standard of ballast water.

Especially, even though planktonic organisms or microbes are notcompletely killed in the ultrasonic sterilizer (200), they are damagedseverely in ultrasonic vibration, and then will be killed completelywhen they pass through the ultraviolet sterilizer (300).

FIG. 8 is a 3D schematic diagram of structure 1 of the ultrasonicsterilizer shown in FIG. 4A and FIG. 4B. As shown in FIG. 8, aprotective cover (230) is arranged outside of the pipe for sterilization(210) of the ultrasonic sterilizer (200).

FIG. 9A and FIG. 9B are longitudinal section views of FIG. 8. As shownin FIG. 9A and FIG. 9B, the ultrasonic sterilizer further comprisesultrasonic vibrators (221) and an acoustic material (231).

FIG. 10 is a plan view of FIG. 8; FIG. 11A and FIG. 11B are 3D views ofFIG. 8, with the protective cover removed. As shown in FIG. 10, FIG.11A, and FIG. 11B, the ultrasonic sterilizer further comprises vibratingplate (222). The ultrasonic vibrator (221) and vibrating plate (222)form ultrasonic irradiation unit (220).

The ultrasonic sterilizer (200) comprises pipe for sterilization (210),ultrasonic irradiation unit (220), and protective cover (230).

The pipe for sterilization (210) is a tubular part, through which theballast water can flow.

The pipe for sterilization (210) is equipped with flanges at both endsfor pipe connection.

The pipe for sterilization (210) has a plurality of ultrasonicirradiation unit (220) mounted on the surface.

The ultrasonic irradiation unit (220) irradiates ultrasonic wave intothe ballast water flowing through the pipe for sterilization (210).

The ultrasonic irradiation unit (220) comprises an ultrasonic vibrator(221) that generates ultrasonic vibration and a vibrating plate (222)that is arranged ahead of the ultrasonic vibrator (221) and tangent tothe ballast water to transfer the ultrasonic wave generated by theultrasonic vibrator into the ballast water.

The ultrasonic vibrator (221) converts electric energy into mechanicalenergy to generate ultrasonic vibration. A variety of forms ofultrasonic vibrators are standardised.

In this embodiment, the vibrating plates (222) are aligned along thelength direction of the pipe for sterilization (210) and tangent to theflow direction of ballast water.

In addition, a plurality of vibrating plates (222) are aligned along thepipe for sterilization (210) on the surface. In this embodiment, 6vibrating plates (222) are aligned at an even interval with gap.

In addition, a plurality of ultrasonic vibrators (221) are arranged inthe length direction of each vibrating plate (222).

FIG. 12 is a 3D schematic diagram of structure 2 of the ultrasonicsterilizer shown in FIG. 4A and FIG. 4B. As shown in FIG. 12, in orderto improve the sterilizing effect of the ultrasonic sterilizer, uppervibrating plates (241, 242, 243, 244, 245, 246) and lower vibratingplates (251, 252, 256) are provided on the ultrasonic sterilizer. Byadjusting the frequencies of ultrasonic vibrators fixed to the uppervibrating plates (241, 242, 243, 244, 245, 246) and lower vibratingplates (251, 252, 256), the cavitation effect in the liquid can beenhanced.

For example, 40 kHz high-frequency ultrasonic wave is generated by the 3upper vibrating plates (241, 243, 245) and 3 lower vibrating plates(252, 254, 256), and 28 kHz lower-frequency ultrasonic wave is generatedby the other 3 upper vibrating plates (242, 244, 246) and 3 lowervibrating plates (251, 253, 255), so that the high-frequency ultrasonicwave and low-frequency ultrasonic wave interact with each other in theliquid, resulting in stronger cavitation effect.

That is because: high-frequency ultrasonic wave has high degree oflinearity and therefore can transfer wavelength intensely into liquid;low-frequency ultrasonic wave can transfer wavelength more intensely,though it has lower linearity compared with high-frequency ultrasonicwave. With that feature, ultrasonic waves with different frequencies caninteract with each other in the liquid.

Whereas the ultrasonic sterilizer (200) generates very high noise due toultrasonic vibration, therefore, the ultrasonic vibrator (221) must haveexterior protection.

To that end, a protective cover (230) is arranged outside of the pipefor sterilization (210).

The protective cover (230) has acoustic material (231) inside. Theprotective cover (230) envelops the ultrasonic vibrator (221) and isarranged outside of the pipe for sterilization (210), so as to reducenoise and protect the ultrasonic vibrator (221) from outside.

FIG. 13A and FIG. 13B are front views of the ultraviolet sterilizershown in FIG. 4A and FIG. 4B. As shown in FIG. 13A and FIG. 13B, theultraviolet sterilizer (300) is connected to the back end of theultrasonic sterilizer (200). The ultraviolet sterilizer (300) isdesigned to kill planktonic organisms and microbes in the ballast waterpassing through the ultrasonic sterilizer by means of ultravioletirradiation.

To achieve that purpose, the ultraviolet sterilizer (300) is equippedwith ultraviolet lamp.

Since the ultraviolet sterilizer (300) is well known in the art, it willnot be described further here.

FIG. 14 shows a metal mesh arranged to enable the ultrasonic sterilizerto transfer ultrasonic wave more effectively. As shown in FIG. 14, themetal mesh (240) arranged to enable the ultrasonic sterilizer totransfer ultrasonic wave more effectively is rolled into circular shape,and arranged inside of the pipe for sterilization (210) such that theoutside of circular metal mesh (240) is tangent to the vibrating plate(222).

Thus, the ultrasonic vibration from the vibrating plate (222) can betransferred not only into the ballast water but also to the center ofthe pipe for sterilization (210) effectively via the metal mesh (240).

Since the metal mesh (240) is a net, it will not hinder the flow ofballast water.

Embodiment 2

FIG. 15 is a system diagram of the ballast water treatment system inembodiment 2 of the present invention; FIG. 16 is a front view of theultraviolet sterilizer shown in FIG. 15. As shown in FIG. 16 and FIG.15, the structure of the ballast water treatment system provided in thepresent invention is such a structure, wherein, the ballast water flowsinto the ultraviolet sterilizer (300) from top, treated with ultravioletirradiation, and then discharged from the top of ultraviolet sterilizer(300).

The system in the present invention can be designed into a structuresuitable for installation at hazardous area of ships, and is anexplosion-proof component.

FIG. 17 is a conceptual longitudinal section view of the explosion-proofultrasonic sterilizer, which is equipped with an explosion-proofprotective cover (261) for the purpose of explosion protection.

FIG. 18 shows oblique view and side view of the explosion-proofultraviolet sterilizing equipment, which is equipped with anexplosion-proof cover plate (310) for the purpose of explosion-proof.

While the above description of present invention is only forillustration, those skilled in the art can be change the above structureinto other structures easily, without departing from the spirit oressential features of the present invention. Therefore, it should beunderstood that all the embodiments described above are illustrative butnot limitative. For example, each component described collectively canbe implemented separately; likewise, components described separately canbe implemented in combination.

The protection scope of the present invention should be only confined bythe claims, instead of above detailed description; all modifications ordeformations of the embodiments are within the protection scope of thepresent invention.

Test Result

A land-based test is carried out for the ballast water treatment systemprovided in the present invention, according to the Guideline forApproval of Ballast Water Management System (G8) issued by theInternational Maritime Organization (IMO). The test result is shown inTable 1.

TABLE 1 Treated Water Influent Control (this IMO California water WaterInvention) Standard Standard High Salinity (Average 32.8 PSU) Vibriocholerae [cfu/100 mL] 5.9+E6 6.7+E5 0 <1 <1 Escherichia coli [cfu/100mL]  1.85+E4 3.0+E3 4 <250 <126 Enterococcus [cfu/100 mL] 1.0+E3 1.0+E30.6 <100 <33 Planktonic organisms 5,780 1,510 0 <10 <0.01 10-50 μM[counts/mL] Planktonic organisms >50 μm  4.66+E5  2.25+E4 0 <10 0[counts/m³] Low Salinity (Average 17.2 PSU) Vibrio cholerae [cfu/100 mL]9.3+E5 1.1+E6 0 <1 <1 Escherichia coli [cfu/100 mL] 9.0+E3 1.3+E3 4.8<250 <126 Enterococcus [cfu/100 mL]   178   541 0.8 <100 <33 Planktonicorganisms 7,680 1,124 <0.01 <10 <0.01 10-50 μm [counts/mL] Planktonicorganisms >50 μm 1.7+E6  6.95+E5 0 <10 0 [counts/m³]

INDUSTRIAL APPLICABILITY

The system provided in the present invention is for use on ships totreat ballast water (sterilization and purification), to preventenvironmental pollution resulted from charge of ballast water into theballast tank or discharge of ballast water from the ballast tank.

[Table of Comparison with Other Techniques] Country BWMS Key AppliedTechnique Advantages and Disadvantages Korea Electro-CleanElectrosterilization Single system: Main streamline flow Techcross Co.,Ltd. without prefilter High cost incurred by electrode exchange andneutralization NKO3 Ozonization Sanitizer is not required: O₃ is(BlueBallast) generated automatically. NK Co., Ltd. Ration supply ofhigh density O₃ High cost incurred by neutralization GloEn-PatrolAutomatic backlash The active substance can be Panasia Co., Ltd. filtercontrolled easily UV (medium voltage) Hard to maintain filter efficiencyEcoBallast Automatic backlash The active substance can be HHI filtercontrolled easily UV (medium voltage) Hard to maintain filter efficiencyJapan Special-Pipe Cavitation & O₃ Sanitizer is not required: O₃ is JAMSgenerated automatically. Very complex system Large noise and high costincurred by high pressure Hybrid BWTS Electrosterilization Singlesystem: Supply without Mitsubishi Group prefilter High cost incurred byneutralization ClearBallast Linking system Very low operation speed: 3minutes Hitachi Group (Fe₃O₄, [Al(OH₂)₆]³⁺) Large size TG BallastcleanerAdding system Continuous supply of chemicals and TG (NaClO, Na₂SO₃)Hazard in storage and management Environmental of chemicals GuardToagosei Group Sweden PureBallast UV and TiO₂ The active substance canbe Alfa Laval Co., controlled easily Ltd. Hard to maintain AOTefficiency EctoSys Electrochemical Single system: Supply without(CleanBallast) sterilization prefilter Permascand AB High cost incurredby neutralization German Peraclean Adding system (15% Continuous supplyof chemicals Degussa GmbH C₂H₄O₃, Explosion-proof in ship 14.3% H₂O₂,26.5% environment CH₃COOH) Ecochlor Adding system with Continuous supplyof chemicals Ecochlor GmbH NaClO₃, H₂O₂&H₂SO₄ Hazard in storage andmanagement (ClO₂) of chemicals Norway Ocean Saver Hydraulic cavitationVery complex system OceanSaver Co., Supersaturation High cost incurredby neutralization Ltd. nitrogen Electrochemical sterilizationNetherlands Greenship Electrosterilization Single system: Supply withoutGreenship Co. Ltd. prefilter High cost incurred by neutralization USAHyde GURDIAN Automatic backlash Hard to maintain filter efficiency HydeMarine Co., filter (disc filter) Ltd. UV (medium voltage) South ResourceBallast Cavitation Very complex system Africa TechnologiesElectrochemical High cost System Resource Ballast sterilizationTechnologies (Pty) Ozone Ltd. Blue Ocean Shield Aqueous medium Largesize due to screen filter and China Ocean cyclone & screen filter lowvoltage UV Shipping Co. & UV (low voltage) High cost due to screenfilter and Tsinghua low voltage UV University China BSKY ™ Water cyclone& US Without active substance and BWMS(this filter byproduct invention)UV (medium voltage) Without chemical additive, without Wuxi harm tohuman being and sea area BRIGHTSKY Low power consumption and lowElectronic CO., cost LTD. Little or no maintenance Low consumptionExplosion-proof

1. A ballast water treatment system, comprising a centrifugal separator,an ultrasonic sterilizer, and an ultraviolet sterilizer, wherein: thecentrifugal separator is designed to separate large-particle of foreignmatters from the ballast water by centrifugal separation by means ofdensity difference; the ultrasonic sterilizer is arranged at the back ofthe centrifugal separator, and is designed to carry out ultrasonicsterilization for the ballast water passing through the centrifugalseparator; the ultrasonic sterilizer comprises a pipe that is used forsterilization of the ballast water and a ultrasonic irradiation unitthat perform ultrasonic irradiation for the ballast water in the pipe;the ultraviolet sterilizer is designed to accomplish sterilization bymeans of ultraviolet irradiation for the ballast water passing throughthe ultrasonic sterilizer; the ultrasonic irradiation unit comprises: anultrasonic vibrator that generates ultrasonic vibration and a vibratingplate that is arranged at the fore-end of the ultrasonic vibrator and isdesigned to transfer the ultrasonic wave generated by the ultrasonicvibrator to the ballast water passing through the pipe; a plurality ofvibrating plates are aligned along the length direction of the pipe forsterilization, and are arranged along the circumference of the pipe forsterilization, and each vibrating plate comprises a plurality ofultrasonic vibrators in the length direction of the vibrating plate. 2.The ballast water treatment system according to claim 1, wherein, theultrasonic vibrator comprises high-frequency vibrator and low-frequencyvibrator, which are arranged alternately in the length direction of thevibrating plate.
 3. The ballast water treatment system according toclaim 2, wherein, in order to transfer ultrasonic wave in the pipe forsterilization, a roll shape metal mesh is arranged inside of the pipefor sterilization and tangent to the vibrating plates.
 4. The ballastwater treatment system according to claim 1, wherein, an acousticmaterial is arranged inside of the ultrasonic sterilizer, and aprotective cover that envelop the ultrasonic vibrators is arrangedoutside of the pipe for sterilization.
 5. The ballast water treatmentsystem according to claim 1, wherein, the diameter of discharge pipe ofthe centrifugal separator increases gradually, the flow velocity offluid increases gradually, thereby centrifugal force increases.
 6. Theballast water treatment system according to claim 1, wherein, aexplosion-proof protective cover for the ultrasonic irradiation unit isarranged on the ultrasonic sterilizer.
 7. The ballast water treatmentsystem according to claim 1, wherein, the ultraviolet sterilizer isfurther equipped with a explosion-proof cover plate.
 8. The ballastwater treatment system according to claim 2, wherein, an acousticmaterial is arranged inside of the ultrasonic sterilizer, and aprotective cover that envelop the ultrasonic vibrators is arrangedoutside of the pipe for sterilization.
 9. The ballast water treatmentsystem according to claim 3, wherein, an acoustic material is arrangedinside of the ultrasonic sterilizer, and a protective cover that envelopthe ultrasonic vibrators is arranged outside of the pipe forsterilization.